1. Technical Field
The present invention is directed toward nebulizers for medicating a patient's lungs and, more particularly, toward an improved disposable hand-held nebulizer.
2. Background Art
Nebulizers are devices for delivering atomized medication to air to be inhaled into the lungs of a patient. A variety of nebulizer structures are known in the medical field. An exemplary nebulizer is that disclosed in Farr, U.S. Pat. No. 4,566,452. Farr discloses a nebulizer having a nebulizer top and a reservoir bottom which are threadably connectable. A gas jet extends from the reservoir bottom along a longitudinal axis of the reservoir bottom. A liquid spray nozzle surrounds the gas jet defining a passageway for liquid between the gas jet and the liquid nozzle. At the top of the gas jet is a gas orifice which leads into a space in fluid communication with the spray nozzle passageway. A second orifice in a top of the spray nozzle is axially aligned with the orifice in the gas jet. A diffuser is connected to the nebulizer top and spaced from the nozzle orifice with the nebulizer top and reservoir bottom threadably connected. As gas is caused to flow through the gas jet, a vacuum is formed in the space between the gas orifice and the nozzle orifice, drawing fluid for nebulization to the fluid nozzle orifice. Nebulized fluid impinges upon the diffuser, causing oversized droplets to stick to the diffuser and providing a finely nebulized mist for delivery to the lungs of a patient.
One problem with nebulizers of the type discussed above can result during filling of the nebulizer reservoir. If a medical professional inadvertently fills the nebulizer reservoir sufficiently that the liquid orifice at the top of the fluid nozzle is covered with medication, medication may be siphoned into the gas jet and out of the reservoir. As a result, medication intended to be delivered to a patient may end up on a countertop as the nebulizer is being connected to an inhalation circuit. This can be a particularly significant problem with expensive medications costing as much as $100/cc or where time is of the essence in delivering the nebulized medication. The siphoning can also lead to build-up of medication in the gas lines, inhibiting proper operation of the nebulizer.
One attempt at solving the siphoning problem discussed above has been to provide a one-way check valve in the lumen of the gas jet. Lester, U.S. Pat. No. 3,762,409, discloses placing a one-way check valve in the gas jet lumen. However, one-way check valves known in the art have proven to be relatively expensive and relatively expensive to install in a gas jet lumen. This presents a significant impediment to providing such check valves, because hand-held nebulizers are molded, disposable assemblies which must be kept as inexpensive as possible to remain competitive in the marketplace. Furthermore, while the cost of the check valve and the cost of installing the check valve must be minimized, the check valve must never fail to permit gas to flow through the gas jet lumen. Should such failure occur, nebulization will be prevented, requiting disposal of the entire hand-held nebulizer assembly. Not only is the cost of the nebulizer wasted, at least residual amounts of potentially expensive medication is wasted. Such problems can result in considerable frustration to the medical professional using the nebulizer and irreparable damage to the goodwill of the nebulizer manufacturer. As a result of the cost and quality assurance problems, we know of no commercially available disposable handheld nebulizer using an anti-siphon check valve in a gas jet lumen.
The present invention is directed toward overcoming one or more of the problems discussed above in a novel and simple manner.